Tunnelling-induced Nonlinear Responses of Continuous Pipelines Resting on Tensionless Winkler Foundation

Prevailing analytical approaches for tunnelling-induced soil-pipeline interactions predominantly rely on linear analyses, limiting their applicability in nonlinear scenarios. This study introduces a novel tensionless Winkler solution that accounts for gap formation and soil yielding, validated against three well-documented experiments and demonstrating superiority over existing Winkler solutions. Additionally, plate load tests refine traditional soil-bearing theories for buried pipelines in sand, providing subgrade stiffness and ultimate bearing capacity values pertinent to tunnelling-induced interactions. Parametric studies highlight amplified nonlinearity in pipeline behaviours with increased pipeline flexural rigidity and tunnel volume loss, due to soil-pipeline separation and subgrade yielding. Notably, ignoring gap formation and soil yielding leads to overly conservative estimations of pipeline deflections and bending moments. Higher subgrade moduli increase pipeline strains, while enhanced subgrade bearing capacity above the pipeline prevents soil yielding, rendering its effect negligible, whereas the bearing capacity beneath the pipeline is inconsequential in tunnelling scenarios.